Dipole and rotating dipole sources result from the fluctuation of the fluid pressure and shear stress field at the boundaries of the CFD domain. Averaged, minimum or maximum values of the pressure or wall shear stress can be monitored in the CFX-Solver Manager using monitor points created in CFX-Pre. The monitor point data will appear in the User Points tab in the CFX-Solver Manager. These data can be exported for external analysis if so desired. For details, see Working with Monitors in the CFX-Pre User's Guide and Exporting Plot Variables and Coordinates in the CFX-Solver Manager User's Guide.

Dipole and rotating dipole source output are built in options for the results export. You simply create an export results object, again with an export surface that uses either the Acoustic Dipole or Acoustic Rotating Dipole options. For these two options, the flow solver automatically writes the necessary data to CGNS files during the run. A single mesh file is written at the beginning of the run, which contains the surface grid coordinates and mesh topology. For rotating dipole sources, the mesh file also includes the normal area vectors in addition to the surface grid and topology.

In both cases, the solver writes the static pressure on the selected boundaries to a file for each timestep. It is important to note that the shear stress contribution to the force on the boundaries is neglected in this case. The second and third terms in Equation 15–6 are ignored. This is normally a reasonable assumption, especially for aerodynamic flows, because the normal force will dominate the noise source.